Aqueous solutions which flow at a controlled rate under a given shear stress are required throughout a variety of industrial applications. Simultaneously, there is enormous need for materials that are ductile at room temperature and can be molded into articles of manufacture or complex shapes. This invention will disclose a unique class of materials that are useful in both applications.
The control of viscosity of water is achieved by adding to water agents, such as clays, amounts of polar organic compounds, such as polyacrylates, or high concentrations of salts. With the appropriate additives, these aqueous solutions can suspend large amounts of a solid phase and form a thermodynamically stable mixture. These aqueous solutions suspend finely divided solids and will flow slowly when exposed to shear stress. Such solutions, free of solids, also flow more uniformly in situations where numerous paths providing different resistances to flow, are open to the fluids.
When a solid must be formed, the materials used to control fluid flow are, generally, not considered. This is because the fluid flow agents form brittle or hydroscopic solids that decompose instead of becoming extrudable when heated. Since materials that can be reformed into articles of manufacture just by heating and plastic processing are very desirable, a large class of compounds which exhibit this behavior have been invented.
However, each of the conventional agents for flow control or solid formation has attendant disadvantages. Hence, a need continues to exist for new agents which are capable of suitably thickening water and aqueous solutions or making objects of manufacture with functional strength and resistance properties. Further, most of the polymeric compounds used in flow control or article manufacture are made from expensive, petrochemical-derived, synthetic chemicals rather than cheaper natural compounds like lignin. Compounds which contain large amounts of lignin are desirable, cheap products because of low raw materials cost. Lignin-containing materials also have a two part structure with the lignin and synthetic parts of the compound tending to phase separate or seek different chemical environments. This difference in affinities produces surface activity which allows the production of very novel thickening agents or plastics. Thickening agents, flow control agents, and thermoplastic solids containing large amounts of lignin are desirable materials because of surface activity, chemical properties, and low materials cost.
Accordingly, it is an object of the present invention to provide a lignin graft copolymer. It is also an object of the present invention to provide processes for preparing the lignin graft copolymer. Moreover, it is also an object of this invention to provide a method for using the above lignin graft copolymer in preparing plastics, both directly and by reacting the lignin polyol with isocyanates to form lignin-containing urethanes. When the products of this invention contain high 2-methyl-3-oxo-4-oxybut-1-ene-(p-ethoxy-(3*p+3)-ol content, the copolymers are crosslinked solids useful in the formation of objects of manufacture. Further, it is also an object of the present invention to provide a method of boosting or enhancing polymer molecular weights during polymerization reactions and lowering polymer glass transition temperatures.